Apparatus for stringing tennis rackets



Jan. 22, 1935.

1.. c, DOLL w 1,989,002

APPARATUS FOR STRINGING TENNIS RACKETS Filed April 21, 1933 2Sheets-Shet 1 w, R dig. ,0

' /v 5k 9 Z /v 5 ,5 /v dag 0 F 0 J" l w-m. W m am" *5 H 1- 1 6 w 1: J 6igwwntoc Patented Jan. 22, 1935 UNITED STATES PATENT OFFICE j APPARATUSFOR. STRINGING TENNIS V aAoKs'rs This invention reiates to certain newand useful' improvements in apparatus for stringing tennis rackets. a 1

The primary object of the invention isto provideapparatus for thestringing of tennis rackets with gut, sill: strings or the like, or forthe tensioning of cables, cords or similar elements wherein an eventension is placed on a series of strings as in a tennis racket.

A further object of the invention is to provide apparatus for thestringing of tennis rackets comprising a stand for the support of aracket with means supported on the stand. andengageable with the racketand carrying a pressure operated string grip under manual control of theoperator for drawing 'the'string through the racket to place the sameunder tension, the support per se for the racket being rotatably mountedupon the stand to present in succession string sections of the racket inline with the pulling force of the stringing apparatus controllable inits operation for placing even tension on all of the strings.

With the above and other objects in view that will become apparent asthe nature of the invention is better understood, the same consists inthe novel form, combination and arrangement of parts hereinafter morefully described, shown in the accompanying drawings and claimed.

- In-the drawings:-

Figure 1 is a perspective view of the stand and support for a racket-tobe strung with the string tensioning device illustrated as adjustablysupported on the stand;

Figure 2 is a detail sectional view showing the rotatable mounting ofthe tennis racket support on the stand; s

Figure 3 is a detail sectional view taken on line 33 of Figure 1,showing the mounting for one of the racket supporting horns on thesupport with a part of a tennis racket illustrated as clampinglyretained in position on the horn;

Figure 4 is a top plan view of the string tensioning device; v

Figure 5 is a longitudinal sectional view taken on line 55 of Figure 4,showing the fluid operated piston carrying the string gripping jaws;Figure 6 is a cross-sectional viewtaken on line 66 of Figure 4, showingthe manually operable pressure fluid supply and exhaust valvecontrolling operation .of the piston carrying jaws;

and

I Figure '7 isa detail sectional view taken on line ,7-'Z of Figure 5,showing the tensioned string gripping jaws;

Referring more in detail to the accompanying drawings, andparticularlyto Figures 1 to 3, there is illustrated an apparatus for thestringing of tennis rackets and for the tensioning of the racket stringscomprising a stand of tripod formation including a perpendicular tubularstandard A having a head block B secured to the upper end thereof withangle legs C connected to the head block B, thestandard A and legs Cbeing provided with floor anchor feet D.

A support per se' for a tennis racket is vertically adjustably mountedwithin the tubular standard A and is also rotatable in the standard in astepby-step movement under control of pawl and ratchet devices, thesupportincluding a shaft E having three arms F horizontally disposed andextendingradially of its upper end, the shaft E being mounted "intubular standard A. As shown in detail in Figure 2, the shaft E passesthrough a disk G that is provided with anaxially depending annularflange H surrounding the opening through which the shaft E passes andsaid flange H is adjustably connected to the shaft E by means of across-pin I extending through diametrically opposite openings in theflange H and selectively through transverse openings J in the shaft E.The flange H seats in an annular pocket K in the upper side of the headblock B and is rotatably retained therein by means of the stud screw Lthreaded radially of the head block B with its inner end extending intoan annular groove M in the flange H. I

To accomplish the step-by-step rotary movement of the racket support,the under side of the disk G is provided with'a circular series ofratchet teeth G with which the tensioneddog B carried by the-stationaryhead block B is engaged. The dog and ratchet devices are so related asto bring the next string opening in the racket frame intopullingalinement with the string tensioning device.

The radial arms F are triangularly arranged as shown in Figure 1 andeach arm is of channel formation and adjustably supports a perpendicularhorn N retained in adjusted positions by the screws 0, the upper end ofeach horn N being shouldered as at P to provide a support for the frameQ of a tennis racket, two of the horns N carrying hinged clamp members Rfor holding the racket frame in position on the horns.

The racket stringing and tensioning device for the strings is carried bya bracket S adjustably mounted asat T upon the tubular standard A,

the upper end of the bracket S being angularly bent as at U to provide ahorizontal shelf support for the string stretching and tensioning deviceV illustrated in detail in Figures 4 to 7.

The string tensioning device comprises a cylinder 10 secured to thehorizontal shelf by means of a screw 10a projecting laterally of thecylinder 10 and extending through a slot 10b in the shelf to receive theclamping nut 100, the cylinder being adjustable longitudinally of theshelf.

The cylinder 10 has a piston 11 reciprocating therein that is normallyinfluenced in its movement toward the end of the cylinder 10 carrying,

the head 29 that constitutes a valve device by means of a coil spring 22having abutting engagement at one end with the cylinder cap 24 retainedin position by the screws 25. The cylinder 11 is provided with an axialbore 11a opening at the end thereof directly toward the end cap 24 andsaid coil spring 22 extends into the bore 11a, the relatively long stud23 carried by the end cap 24 providing a guide support for the coilspring 22 and extending into the bore 11a of the piston 11. The cylinder10 is longitudinally slotted as at 10d at a point substantially midwayits ends to the end adjacent the cap 24 for the clearance of stringgripping jaws carried by the piston 11. i

As shown more clearly in Figures 5 and 7 a block 13 is secured by meansof screws 12 to the piston 11 and is slidable in the slot 10d, the block13 being cut away at its outer side for the reception of a pair ofcooperating wedge shaped string gripping jaws 14 that have their opposedfaces suitably fashioned for gripping engagement with a racket stringwithout in any manner injuring the latter. The opposed'faces of thegripping jaws l4 and the block 13 are relatively inclined to causemovement of the jaw members 14 toward each other when they are shiftedlongitudinally of the block 13, the opposed faces of the wedge shapedjaw members and block 13 being further cut away to provide matingrecesses for the reception of coil springs 17 acting to maintain thejaws 14 in string gripping relation. The jaws 14 are guided in theirmovement by means of pin and slot connection between the jaws 14 andblock 13. A pair of spaced cover plates 15 overlie the jaws 14 and aresecured to the block 13 by means of screws 16. When the piston 11carrying the string gripping jaws 14 is disposed at the end of thecylinder 10 adjacent the valve head 29 underinfluence of the spring 22,the normally projecting ends of the jaws 14 as shown in Figures 4, 5 and7 are in engagement with an abutment block 21 carried exteriorly of thecylinder 10 said block serving to hold the string gripping jaws 14separated from one another against the tension of the spring devices 17for receiving a racket string therebetween. As soon as the piston 11moves in the cylinder 10, the springs 17 exert their force to shift thewedging string gripping jaws 14 into engagement with a string, the jaws14 being displaced from the abutment lug 21. The outer end of the piston11 has a flexible gasket 26 secured thereto by means of a metallicwasher 2'7 and set screws 28 entering the outer end of the piston withthe gasket moving in working contact with the inner wall of the cylinder10.

The valve head 29 embodies manually operated devices designed for theintroduction of fluid under pressure to the outer end of the cylinder 10for moving the piston 11 against the tension of the spring 22' and toaccomplish the exhausting of fluid from the cylinder to permit thespring 22 to shift the piston 11 to the position shown in Figure 5. Thevalve head 29 is provided with a transverse bore 29a in which a valvestem 30 is reciprocably mounted, one end of the valve stem 30 beingsocketed as at 30a with the socketed end directed toward a cap 32secured by means of set screws 33 to a tubular boss 29b carried by thevalve head 29. .14 pin 32a carried by the end cap 32 projects intothe'recess 30a in the Valve stem 30 and is surrounded by a coil spring 31engaging the inner side of the cap 32 and the bottom of the recess 30ain the valve stem 30 for normally shifting the valve stem 30 to a closedposition relative to fluid supply passages or bores through the valvehead 29. The side of the valve head 29 opposite the cap 32 carries atubular boss 290 into which the valve stem 30 extends and the outer endof said boss 290 carries an end cap 3'7 secured thereto as at 38 andprovided with a slotted opening for the projection of the handle 34acarrying a button 34 at its outer end, the handle 340. being pivotallyconnected by means of a cross pin 35 at its inner end to the adjacentend of the valve stem 30. The handle 34a is provided with a shoulder 36to be engaged by the part of the cap 37 for retaining the valve stem 30projected in open position for the flow of fluid under pressure to thecylinder 10 and against the tension of the spring 31 engaged with thevalve stem 30. A flexible conduit or other conductor 39a in communi-'cation with a source of fluid of any character under pressure isattached to the nipple 39 entering the lower side of the valve head 29and said valve head has a port 2911 extending between the supply nipple39 and the bore 29a of the valve head. The valve stem 30 has an angleport 301) therein that is normally out of communication with the port29d in the valve head as shown in Figure 6 and this angle port 301) isalso normally out of communication with the port 296 in the valve headthat is shown in Figure 5 as extending between the cylinder 10 and thebore 29a in the valve head. With the valve 30 in the position shown inFigure 6, the port 29d is closed by the valve and the port 300 in thesocketed end of the valve is in communication with the port 29c as shownin Figure 5. When the valve 30 is shifted against the tension of thespring 31 by manual operation of the handle 34a, the angle port 30bforms communication between the ports 29d and the port 29c so that fluidunder pressure flows into the cylinder 10 for moving the piston 11against the tension of the spring 22. To exhaust the fluid from thecylinder 10 and to permit the spring 22 to move the piston 11 in thecylinder for freeing the jaws 14 from engagement with the racket string,the valve 30 is shifted to the position shown in Figure 6 for closingthe supply port 29d and bringing the port 300 into registry with theport 29c, as shown in Figure 5 whereupon fluid trapped in the cylinder10 flows into the socketed end 30a of the valve to escape through theexhaust port 32b in the cap 32. .A pair of spaced lugs 40 rises from theupper side of the valve head 29 for abutting engagement with the frameof the racket Q with the racket string passing between the lugs 40 andengaged with the string gripping jaws 14.

In the use of the device, a tennis racket Q is engaged with theshoulders P of the horns N, retained thereon by the clamp R and one ofthe openings in the bracket Q is aligned with the string stretching andtensioning device V. The lugs 40 are abuttingly engaged with the frameof the rocket Q and the racket thread is passed between the lugs 'ii-andis'threadedintothe open space betweenthe gripping jaws 514'. The valvestem 30 isthen shifted'by means of the'operating head 34against thetension of the spring 31 to move the port 30cinto registry with the port29e,'--'and'at which time fluid undera predetermined'pressureisdirectedinto the outer end of the cylinder for moving the piston 11therein against the tension of the spring 22. As soon as the grippingjaws 14 are spaced from the abut ment lug 21 the springs 'lt associatedwith the gripping jaws 14' cause the latter to grippingly engage theracket string, continued movement of the piston 11 under influence offluid pressure placing the racket string under tension. A suitable wedgeor the like isthen inserted in the thread opening in the frame of theracket Q' for retaining the stretched string'at the tension placedthereon bythe device. When the valve stem 80 is shifted to its retractedor closed position by means of the spring 31, the supply of fluidlunderpressure is cut ofi and-fluid trapped inthe'cylinde'r- 1i) escapesthroughthe-valve head 29 which restores the piston 11f to the positionshown in Figure 5 for the release of the-racketstring from the grippingjaws 14; The racket support is then rotatably'shifted a single'step bymeans of the pawl and ratchet devices G and B to present the nextopening in the racket frame in line with the abutment lugs 40 andgripping jaws 14, whereupon the stretching and tensioning operation onthe string is repeated. It will be seen that an even tension can beplaced on all the strings of a tennis racket and the tension of thestrings of different rackets may be varied under control ofpredetermined pressure of fluid supplied to the device. It is to beunderstood that the fluid operated string stretching and tensioningdevice may be operated either pneumatically, hydraulically or in anypreferred manner and the statements herein referring to fluid operationis not to be con-, strued as limiting the invention to the character ofmotivating forces.

While there is herein shown and described the preferred embodiment ofthe invention, it is nevertheless to be understood that minor changesmay be made therein without departing from the spirit and scope of theinvention as claimed.

I claim:

1. In a stringing and tensioning device for tennis racket strings, asupport for a tennis racket, a string stretching and tensioning deviceassociated with the support and including a cylinder, a fluid operatedtensioned piston therein, string gripping jaws carried by the piston andvalve means for controlling the supply and exhaust of fluid underpressure to the cylinder, and lugs carried by the cylinder for abuttingengagement with the racket in opposition to the string pulling force ofthe jaws.

2. In a stringing and tensioning device for tennis racket strings, asupport for a tennis racket, a string stretching and tensioning deviceassociated with the support and including a cylinder, a fluid operatedtensioned piston therein, string gripping jaws carried by the piston andvalve means for controlling the supply and exhaust of fluid underpressure to the cylinder, and means carried by the cylinder to beengaged by the jaws for disengaging the jaws from the racket string.

3. In a stringing and tensioning device for ten nis racket strings, asupport for a tennis racket, a string stretching and tensioning deviceassociated with the support and including a cylinder,

a fluidoperated tensionedipiston therein, string gripping jaws carriedby the piston and valve means for controlling the supply and exhaustoffluid under pressure to the cylinder, and lugs carried by the cylinderfor abutting engagement with theracket in oppos'ition'to the stringpulling force ofthe jaws, and means carried by the cylinder to beengaged by the jawsior disengaging the jaws from the racket string.

4. In a stringing and tensioning device for tennis racket strings, asupport for a tennis racket, a string stretching and tensioningdeviceassociatedv with the support and including a cylinder, 2. fluidoperated tensioned piston therein, string gripping jaws carried by thepiston and valve means for controlling the supply and exhaust or fluidunder pressure to'the cylinder, the support including a rotatable frame;a stationary stand supporting the frame and pawl and ratchet devicesbetween the frame and stand whereby the support is rotated in a step-bystep movement for the successive tensioning of the racket strings.

5. In a stringing and tensioning device for tennis racket fstrings,fasupport for a tennis racket,

a string stretching and tensioning device. associated with the supportand including a cylinder, a'fluid operated tensioned piston therein,string grippingv jaws carried by the piston andvalve means forcontrolling the supply and exhaust of fluid' under pressure to thecylinder, means carried by the cylinder to be engaged by the jaws fordisengaging the jaws from the racket string, the support including arotatable frame, a sta tionary stand supporting the frame and pawl andratchet devices between the frame and stand whereby the support isrotated in a step-by-step movement for the successive tensioning of theracket strings.

6. In a stringing and tensioning device for tennis racket strings, asupport for a tennis racket,

, a string stretching and tensioning device associated with the supportand including a cylinder, a fluid operated tensioned piston therein,string gripping jaws carried by the piston and valve means forcontrolling the supply and exhaust of fluid under pressure to thecylinder, and means carried by the cylinder to be engaged by the jawsfor disengaging the jaws from the racket string, the support including arotatable frame, a stationary stand supporting the frame and pawl andratchet devices between the frame and stand whereby the support isrotated in a step-by-step movement for the successive tensioning of theracket strings.

7. In a stringing and tensioning device for tennis racket strings, asupport for a tennis racket, a string stretching and tensioning deviceassociated with the support and including a cylinder, a fluid operatedtensioned piston therein, string gripping jaws carried by the piston andvalve means for controlling the supply and exhaust of fluid underpressure to the cylinder, and lugs carried by the cylinder for abuttingengagement with the racket in opposition to the string pulling force ofthe jaws, and means carried by the cylinder to be engaged by the jawsfor disengaging the jaws from the racket string, the support including arotatable frame, a stationary stand supporting the frame and pawl andratchet devices between the frame and stand whereby the support isrotated in a step-by-step movement for the successive tensioning of theracket strings.

8. In a stringing and tensioning device for tennis racket strings, asupport for a tennis racket, a string stretching and tensioning deviceassociated with the support and including a cylinder, having a sideslot, a piston in the cylinder,'-a block fixed to the piston andprojecting through the slot,.a pair of tensioned string gripping jawscarried by the block and means for moving the jaws to disengagingposition relative to the racket string when the piston is at its limitof movement in one direction. a

9. In a stringing and tensioning device fortennis racket strings, asupportfor a tennis racket, a string stretching and tensioning deviceassociated with the support and including a cylinder, having a sideslot, a piston in the cylinder, a block fixed to the piston andprojecting through the slot, a pair of tensioned string gripping jawscarried by the blockand means for moving the jaws to disengagingposition relative-to the racket string when the piston is at its limitofmovement in one direction, valve meansfor controlling the supply offluid under pressure. to the cylinder and a spring associated with thepiston for moving the same to exhaust fluid from the cylinder when thesupply valve is closed.

10. In stringing and tensioning mechanism for tennis racket strings, asupport for a tennis racket, and a string stretching and tensioningdevice having means engageable with the outer side of the racket andfluid operated means aligned with the aforesaid means engageable with, aracket string outwardly of the racket for effecting a pulling strain, onthe string in opposition to the means engaged with the racket,

11,. In stringing and, tensioning mechanism for tennis racket strings, asupport fora tennis racket, and a' string stretching and tensioningdevice having means engageable with the outer side of the racket andfluid operated means aligned with the aforesaid means engageable with aracket string outwardly of the racket for effecting a pulling strain onthe string in opposition to the means engaged." with the racket, thefluid operated means including a-pair of slidablytensio'ned wedging jawsand a movable member carrying the jaws.

12. In stringing and tensioning mechanism for tennisracket strings, asupport for a tennis racket, and a string stretching and tensioningdevice having means engageable with the outer side of the racket andfluid operated means aligned with the aforesaid means engageable with aracket string outwardly of the racket for effecting a pulling strain onthestring in opposition to the means engaged with the racket, the fluidoperated means including a pair of slidably tensioned wedging jaws and amovable member carrying the jaws, and-means associated with the movablemember for normally positioning thev wedging jaws for releasingengagement relative to the string. LAURANCE c. DOLL.

